[Dynamo][Better Engineering] Type annotation for torch/_dynamo/output_graph.py (pytorch#159602)

As part of better engineering effort, we would like to improve out type support to improve dev experience in dynamo

This PR adds strict typing support to `torch/_dynamo/output_graph.py`

Running
```
mypy torch/_dynamo/output_graph.py --linecount-report /tmp/coverage_log
```

| -------- | Lines Annotated | Lines Total | % lines covered | Funcs Annotated | Funcs Total | % funcs covered |
| -------- | ------- | -------- | ------- | ------- | ------- | ------- |
| Main  |  2163 | 4792 | 45.14% | 121 | 268 | 45.15% |
| This PR | 4818 | 4818 | 100.00% | 268 | 268 | 100.00% |
| Delta    | +2655 | +26 | +54.84% | +147 | 0 | +54.85% |

Pull Request resolved: pytorch#159602
Approved by: https://github.com/Skylion007

Author: Lucaskabela